This invention relates to a door control; and in particular to a heat-actuated door latch, which is used advantageously in combination with a door-closing-arm holder and release which effects free swinging of the door in non-emergency conditions and closes the door during an emergency.
In buildings housing elderly or infirm persons, life safety is of primary importance. These persons generally require the assistance of others in the event of an emergency since they have limited strength and mobility. Additionally, their response to emergency situations is slower than is that of normal persons, thus dictating a shorter time period for life saving measures. Accordingly, buildings designed primarily to house the elderly or infirm are required to meet more stringent life safety requirements than those designed for ordinary use.
One of the life safety requirements for such buildings may require the installation of automatic or alarm actuated door closers to confine smoke or flame.
In the usual installation, the door closer is of the automatic type, employing either a hydraulic or spring-loaded closing force. Such a closer exerts a force on a door at all times when it is opened. Thus, anyone at any time going through a door equipped with such a closer must overcome the closing force of the closer to pass through the doorway.
Door holder-closers, which are released in response to an emergency condition, all contain a similar undesirable feature. They are attached directly to the door and require the exertion of a manually applied force to open the door to overcome the closer under normal or non-emergency conditions.
The usual forces required to open a door, which is of no consequence to normal, healthy persons, are formidable obstacles to the elderly or infirm, and may be tiring or irritating to attendant staff members of a nursing home or hospital. The day to day inconvenience of pushing against door closers to both the residents and the attending staff has caused the removal of these devices in violation of the fire safety codes.
A second major objection to the use of automatic or alarm actuated door closers and door holder-closers relates to the relatively large installation and maintenance cost of these devices.
With respect to the high cost of using automatic door closing devices on room-to-corridor doors (patient room door), a cost reduction would be possible if existing latching hardware could be eliminated. Although room-to-corridor door requirements vary throughout the country, one consistent requirement is that doors must be latched closed in the event of fire. This is true whether automatic closing of doors is or is not required. Without latching, the pressure buildup during a fire may force a closed door open.
Latching of doors may be accomplished for patient room doors by the following devices: standard type latch sets, hospital type latch sets, and roller latches.
Standard latch sets are not often used because they require a free hand to unlatch the door. This can be a problem for attendants and occupants entering or exiting rooms.
Hospital latches overcome this problem with specially designed handles which permit unlatching to be accomplished with the elbow or forearm. These devices are substantially higher in cost than standard latch sets.
Roller latches need only push-pull hardware for opening and closing doors; however, they do not effect positive latching. The forces required to open and close doors vary from extremely high (over 10 lbs.) to no force at all, that is, little or no resistance to opening which may not keep the door closed under fire condition pressures.
All three of the above latching means have objectionable features. If the conventional latching devices could be eliminated and incorporated in an automatic closing device modified for a free door swing, for a slight cost, and perform only their function during a fire situation, it would eliminate the existing objections.